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Be aware, that it doesnt matter where the hammer is, if you look to the physics of a lever. The 200% arrows are as accurate as I could do.This is exactly the middle point between pivot axis and keyfront.Fatar TP100 looses definitely. It is however, only a small difference so go into the next musicstore and try out, if this matters to you

I find this is a much more important criteria to compare a digital action to a grand piano action.

Heavy and graded weighting is something that the piano builders fight. They try to minimize it.They try to maximize keylenght.

So the advertising arguments that are sometimes given to unknowing people are somewhat misleading.

No DP reaches a grand and most dont even reach a lower class upright in keylength.

So many DP's just combine the disadvantages of a Grand -heavy grading and weighting- with the disadvantage of an upright - short keys.This is then advertised and sold as a accurate modelled grand action. They all tell lies to their unknowing customers ;-)

Yes they all try to get a good touch and feel, but none of them tries seriously to emulate the most important and basic and obvious physical parameters of a grand action accurately, because thats too expensive.

Because grading and weighting are also attributes of uprights, (and match much better) the comparison to a grand is nothing else than intentional misinforming advertising.

From this it turns out that the differences between the big manufacturers Yamaha, Roland and Kawai are almost neglectible.There is only one clear looser: Fatar TP100. Casio is only lightly better.Therefore I removed all other comments.

Edit: If it comes however to the length of black keys, then Kawai RM3 wins definitely because it has a shifted pivot point.This is not visible here.

I'd bet you could make a good digital action with zero length keys. Length may matter if the hammers have to strike strings but thy don't on a DP. One way you could build a DP is to use electric linear motors under the keys and the moors could produce force to simulate any kind of action. This was actually done (I lost the refference buy Google can find it.) They made the elxtonic key, then "sampled" the pressure from variious pianos actions and could simulate in near perfectly. This would be great because you could have your keys feel like any piano (or organ) you like. The trouble is the cost, more then the cost of a current DP for each key. Maybe if it were mass produced it could go down to only a few hundred dollars per key, but you need 88 of them.

In the past some DPs used oil dampers so simulate key mass or I should say "the mass of the moving parts in the acton" this worked but they found cheaper and more reliable methods.

I think also that we are turning a corner. Look at Yamaha's new "Stage-NW" keys. I think they've decided not ot even try to emulate an acoustic piano. Most of the people who buy the DP will use that DP as their performance instrument on stage and will never play an acoustic piano. Over tie more and more people will stop comparing a DP to an Acoustic Piano.

@hPeter; exellent work, but I don't unstand what we are looking at here. Perhaps I missed some previous threads with explanation, but could you please describe what we are seeing here in this comparison with pictures and which one is better than the other and what the perfect target should be ? It would make things easier to understand. Thanks

The initial image explains it.I look solely to this singular and measurable aspect of relative key-lever length, no other aspects are covered here.I do however assume that the visible length of piano keys is standardized and therefore comparable. I am unable to measure and compare this using images only.

I must be dumb and stupid, but since I have no clue as to what you are showing here, it's hard for me to read and understand the picture and the 200% arrow that you put in each one.

Does this mean that the 200% fingerforce point should be shifted backwards (from you) as far as possible and that 100% is the ideal striking force ? And that keybeds that are not so good have their 200% point more on the front of the key , which gives a unnatural and heavy response ?

As far as I can see the 200% arrow is all in roughly the middle of the key, so am I missing the point you're trying to make here ?

Pitty that some brands have no better pics posted , as with the Casio keys and FATAR's. I already found that strange in the past when I was looking for a DIY way to build a piano - which I later abandoned. (For the manufacturer: if these pics are hardly readable why post it at all...)

One way you could build a DP is to use electric linear motors under the keys and the moors could produce force to simulate any kind of action. This was actually done (I lost the refference buy Google can find it.)

Yes, and we've already discussed it HERE in another thread:this thread

As far as I can see the 200% arrow is all in roughly the middle of the key, so am I missing the point you're trying to make here ?

Yes, thats true. You must look to the relative dimension of the black key. This is not equal.(I assume that the real absolute dimensions of the black keys is mostly identical because this is standardized. Of course I cannot measure this using these images)

The images are scaled this way that the key lever length is identical. There is no other way for comparison without having the real absolute dimensions.Also look to this posititon where the white touch surface ends.This is also unequal. There is some guesswork and eyeballing necessary, but I think, it can be seen there is a large difference between the real grand and the digitals.

And for the white key there is not much difference between Yamaha Roland and Kawai.

However, Kawai's RM3 has a longer lever for the black key than the others. This is not shown or discussed here.That said, I am not too much concerned about the length of the black keys. These are easy to hit and depress. The difficulty is to play the white keys inbetween of the black keys. I dont understand why they didnt shift all pivots ....

I am not too much concerned about the length of the black keys. These are easy to hit and depress. The difficulty is to play the white keys inbetween of the black keys.

Actually, I find the bigger issue to be on the black keys (at least on some semi-weighted keyboards I've played, where I've noticed it the most), and I think your diagram demonstrates the problem.

Play an Eb chord, then play an Eb minor chord... you'll probably find that, on the minor chord, your middle finger kits the key much closer to its rear end. At that point, on some key designs, you're quite close to the pivot point, and the amount of finger force required to get the same volume is much higher.

The Korg SP-200 that I have suffers from this problem. The force required on the back half of the keys is much greater than at the front and difference for the black keys in particular is dramatic and unrealistic compared to the force required on my Kawai RX-2

Surely the deciding factor is what the key action feels like to the performer? Even grand piano action differs between different makes, and I don't just mean the weight of the keys. And of course uprights feel totally different to grands. I find that my V-Piano's key action is closer to a concert grand's than most uprights are.

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Yes, but I do not want compare cherrys to oranges.I want to look to the differences between them.Not all grandpianos are created equal.Not all upright are created equal.But most digitals have something in common.Therefore I updated my images for better clarity.See above.

Peter, thank you for all you effort to demonstrate a VERY important parameter in piano action. In my experience, the longer the distance of the fulcrum the better the action feels while playing. One of the reasons, as you point out, is a better uniformity of the weight along the key.

I would add to that also a better uniformity in key travel distance. If the fulcrum is too close, when your fingers get closer to the fallboard, not only the weight increases but also the key travel decreases and it gets very difficult to properly control the timing and the intensity of the sound.For example, when you play octaves with your right hand below the center of the keyboard on the black keys (1-4 fingering) the fourth finger gets naturally very close to the fallboard. The same happens on the white key between the sharps when you play four notes chords like Eb7.

In the case of the octaves I described, on my P90 the thumb gets a travel of approximately 9mm while the fourth finger has only 3,5mm (plus a much higher key weight) - VERY difficult to play the two notes perfectly in sync. I can feel my hand getting rigid and tired from the effort. This is much easier to play correctly on the C3. And even better on a real grand.I think we are very, very far, on almost all the DPs, from the keyboard quality and experience of a grand action.

Yes, thanks Peter - I had never really thought about all this at all. It's a bit depressing that DP makers seem to have paid so little respect to the grand's action for so long! I now have a full appreciation of the advantage of the offset fulcrum points in the Kawai RM3 action.

Ok I have reached the limit of images so I need to add another post.I believe this image is worth it.

This is the action of the Yamaha Gran Touch GT1.Surprisingly the 200% location is very similar to other digital pianos.So when this action feels so much better then there must be another factor thats important: The overall leverage ratio Key-hammer.This is 3 or less for most digitals. Unfortunately it is not precisely visible from this image, but for large grands it is up to 6.

This ratio is the ratio between weight and massinertia (if the keys mass is neglected)

BTW, it seems to me, pianists are a little bit like the princess and the pea when it comes to the feel of the action. Im now asking myself: does this all really matter?

Of course it is pure Nonsense to compare any digital -including the Gran Touch- to a larger Grand Piano... Baby grands have longer keys.

Look here a Kawai six foot CA60. You see the length of the keys at 1:40 for a very short time.

It is rewarding to look into this guys channel because he shows off the action of many pianos that he has for sale.

Of course it is pure Nonsense to compare any digital -including the Gran Touch- to a larger Grand Piano... Baby grands have longer keys.

Look here a Kawai six foot CA60. You see the length of the keys at 1:40 for a very short time.

Manufacturers usually fit longer keys to their models at approximately their seven feet long models. (The CA 60, for example, is said to be 6'10".)

Originally Posted By: hpeterh

This is the action of the Yamaha Gran Touch GT1.Surprisingly the 200% location is very similar to other digital pianos. So when this action feels so much better then there must be another factor thats important: The overall leverage ratio Key-hammer. This is 3 or less for most digitals. Unfortunately it is not precisely visible from this image, but for large grands it is up to 6.

BTW, it seems to me, pianists are a little bit like the princess and the pea when it comes to the feel of the action. Im now asking myself: does this all really matter?

It does matter, but ultimately people have to choose based on how an action feels to them. That decision will be influenced by their previous playing experience - and budget, of course!

For the key length (and hence, key movement) aspect, I guess there are two aspects:

a) How long, in absolute terms, do the keys have to be for a human to play very advanced material?

b) How long do the keys have to be in order for a concert pianist to be able to easily switch between a concert grand and the other keyboard, that has shorter keys?

I.e - perhaps the key lengths in an upright are ENTIRELY adequate, and the only reason they are longer in a large concert grand is simply because they HAVE to be, in order for the pianist to be able to have enough leverage to play loud enough.

Hammers are usually placed at 1/5 to 1/7 of string length.They are placed this way that the 7th harmonic is almost surpressed.Thats another reason for the keys being longer.

For a nine foot the keys are about 30% longer than for a 6 foot for this reason.

I believe anybody should be happy with the keylentgh of a 6 foot baby grand, but no digital -including the Gran Touch- does reach this.

With uprights the pianodesigners have more degrees of freedom for the keylength.Maybe we should look to the keylength of uprights that are commonly aknowledged for their action to get a reasonable measure about this.

Hmmmm... I don't see the point by mainly focusing on the keylength as a major criterium for realism of keyboard action. According to your interesting illustrations I don't see a lot difference in pressure, except for the grand. Don't forget that long keys also have some downsides, e.g. it might take longer for the keys to release back to the starting position due to a different inertia depending on mass. I think there are a lot more criteria that are even more important than a little bit more or less keylength.

When the mass increases the resonance frequeny goes down.The amount of bounce back energy increases.When the elasticity of the felts become stiffer , the frequency goes up again, but the forces needed will be higher.

Therefore keylength does not necessarily make the action slower, but increases mass inertia and forces.That are the physical facts.

Yes.A counterweight thats near to the center balance does not increase mass inertia much. (This is why the weights are placed this way)

If a 5 gramm weight is placed 20 cm from center and a 10 gramm weight is placed 10 cm from the center then both have the same effect on weight. But in that case the 10 gramm weight has less effect on inertia than the 5 gramm weight ;-)This can be calculated with some physics, but any pianotechnician can confirm it.

A little bit of key inertia might be wanted for comfort of touch, it can buffer the hammer bounce, but anything more than that is generally unwanted and fighted by piano builders.

In modern designs the weights are replaced by magnets.Because these dont cause inertia they can be placed at the hammer where they are far more efficient because there is more leverage effect. The inertia must be located in the hammers and the pianist wants to feel the hammers inertia at the key touch surface.

Can I ask (without being punished) ; after all these pictures , measurements and explanations - do you have a short list of the keybeds that are used in DP's from best to worst ? E.g. how do PHAII, PHAIII, RM3, RH, GH3, Tp40Wood etc meassure up to your 'ideal' grand piano keybed. It think that might be very interesting for potential Dp buyers to know.

short answer - no.I just want to know the technical criterias,thought a lot about it, recherched about it, experimented with it, and finally calculated the physics, got some results and want to show them.

Ok, let me rethink - most probably the Avant Grand is the best digital ;-)